Apparatus for delivering air through powered axle assemblies

ABSTRACT

An apparatus for delivering air through a powered axle assembly for use in automatic tire inflation systems. The apparatus comprises a base attachable to a non-rotating structure within the axle assembly and having the drive axle extend therethrough. A rotor is mountable in the axle assembly for rotation with the drive axle and for forming an air chamber between the rotor and the base and extending about the drive axle. An annular sealing member in sealing engagement with the rotor and the base is disposed within the air chamber and is rotatable with the rotor and with respect to the base. The base includes at least one air inlet for delivering air in a radial direction into the air chamber and the rotor includes at least one air outlet for air flow out of the chamber.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional application of pending U.S. patent application Ser.No. 14/328,617, filed on Jul. 10, 2014, entitled “Apparatus ForDelivering Air Through Powered Axle Assemblies.”

FIELD OF THE INVENTION

The present invention relates to apparatuses for delivering air throughpowered axle assemblies and to improved powered axle assemblies havingsuch apparatuses incorporated therein.

BACKGROUND OF THE INVENTION

Onboard automatic tire inflation systems are currently available for useon trucks and other vehicles. Such systems have been successfully usedin non-powered vehicle axle assemblies (i.e., the axle assemblies oftrucks or other vehicles which do not include powered drive shaftslinked to the vehicle differential or other drive system) to delivermake-up air to a vehicle tire in the event that the tire is punctured orbegins to leak or for other reasons, e.g., controlling the tire pressurebased on road conditions.

By way of example, an onboard system for maintaining a predeterminedpressure in each of the tires of a non-powered truck tandem axleassembly is currently available from Airgo, Inc. of Edmond, Okla. TheAirgo system delivers compressed air from an onboard compressor (e.g.,the compressor used for supplying air to the truck brakes) to theinterior of the tandem axle, or to a tube extending through the axle, inthe event that a leak occurs in any of the four tandem axle tires. TheAirgo system also includes: a pair of rotary seals provided proximatethe outer ends of the non-powered tandem axle; a set of air linesextending from the rotary seals for delivering air from the interior ofthe axle, through the rotary seals, to each of the four tires; checkvalves provided in the air lines for preventing reserve air flow fromthe tires to the axle; and an indicator light which alerts the operatorthat a leak has developed. The system controls the make-up air flow inaccordance with the operating pressure required by the tires. For mosttandem truck axles, the automatic inflation system will typically beoperable for providing a sufficient make-up air flow to maintain a tirepressure of at least 90 psig and more preferably at least 95 psig. Anonboard automatic inflation system of this type is described, forexample, in U.S. Pat. Nos. 6,105,645 and 7,418,892, the entiredisclosures of which are incorporated herein by reference.

Although the rotary union assembly employed in the Airgo system allowsthe use of onboard automatic tire inflation systems in non-powered axleassemblies, the development of a commercially viable system which wouldallow the use of such onboard automatic tire inflation systems in thepowered drive axle assemblies of trucks and other vehicles proved to bemore problematic due to the presence of the rotating axle within thespindle. Commercially viable systems for non-powered axle assemblieswere not adaptable for use on drive axles and the available drive axlesystems usable on other types of vehicles had significant shortcomingsand disadvantages. For example, such systems (a) would typically inflateonly during a portion of the revolution of the tire or only when thevehicle was stationary, (b) could not operate at highway speeds, (c) didnot provide continuous seal lubrication, (d) were not self contained,and/or (e) required external components which did not fit with theexisting axle assembly.

Subsequently, Airgo, in cooperation with Oklahoma State Universitydeveloped a new rotary union assembly for use in an automatic tireinflation system for powered drive axle assemblies which is the subjectof U.S. Pat. No. 7,896,045, the entire disclosure of which also isincorporated herein by reference. While the new rotary union assemblyoperated as intended, it was comprised of multiple components,increasing its cost of manufacture and making it difficult to assembleand susceptible to leakage. The assembly also introduced air into therotary union in an axial direction as was typical of the availablerotary union assemblies for non-powered axle assemblies. The force ofthe axially directed incoming air tended to push outwardly on the rotaryunion and caused the components thereof to tend to separate in the axialdirection which could result in the loss of the seal between therotating and non-rotating components. This issue became more significantin the event of off center wheel mountings due to the resulting wobbleof the rotating portions of the assembly with respect to the stationaryportions. The combination of wobble and high pressure axial air flow cancause the seal to periodically disengage from its contact surfaceincreasing the possibility of leakage. To reduce the wobble caused byoff center mountings, customized spacers were employed for each axlevariation, due to the inconsistencies in the distance from the front ofthe spindle to the back of the axle plate. Development efforts continuedand the aforesaid shortcomings with the prior drive axle system havebeen obviated by the present invention.

SUMMARY OF THE INVENTION

The present invention provides an apparatus for delivering air through apowered axle assembly which satisfies the needs and alleviates theproblems discussed above. The inventive apparatus can be used inconjunction with onboard automatic tire inflation systems currentlyavailable and will not interfere with the operation of the drive axleassembly. Moreover, the inventive apparatus can be readily adapted formaintaining inflation in individual tires or in the dual or othermultiple tire sets of the powered axle assemblies of trucks and othervehicles.

In one aspect of the present invention, there is provided an apparatusfor delivering air through a powered axle assembly, the powered axleassembly including a drive axle which extends through a non-rotatingstructure and is powered for rotation with respect to the non-rotatingstructure. The apparatus comprises a base attachable to a non-rotatingstructure and a rotor mountable for rotation with the drive axle suchthat the rotor will rotate with respect to the base and is configured tocooperate with the base so as to form an air chamber therebetween. Thebase includes at least one air inlet configured for delivering air intothe air chamber in a radial direction and the rotor includes at leastone air outlet for air flow out of the air chamber. An annular sealingmember, preferably having a plurality of openings extending radiallytherethrough, is provided within the air chamber between said air inletand said air outlet for forming a seal between the rotating rotor andthe stationary base.

In another aspect of the present invention, there is provided animproved powered axle assembly including a drive axle which extendsthrough a non-rotating structure and is powered for rotation withrespect to the non-rotating structure. The improvement comprises a baseattached to the non-rotating structure and a rotor mounted for rotationwith the drive axle such that the rotor will rotate with respect to thebase and is configured to cooperate with the base so as to form an airchamber therebetween. The base includes at least one air inletconfigured for delivering air into the air chamber in a radial directionand the rotor includes at least one air outlet for air flow out of theair chamber. An annular sealing member, preferably having a plurality ofopenings extending radially therethrough, is provided within the airchamber between said air inlet and said air outlet for forming a sealbetween the rotating rotor and the stationary base.

In another aspect of both the improved apparatus and powered axleassembly of the present invention, an annular sealing member of thedouble-lip seal type having a plurality of openings extending radiallytherethrough is disposed within the air chamber formed between the rotorand the base and is positioned in a balanced disposition about the atleast one air inlet in the base so as to form an efficient low frictionseal between the rotating rotor and stationary base over a broadpressure range while uniformly distributing the axial forces generatedby the air flow within the cavity thereby minimalizing the effect of anyoffset wheel mountings on the rotary seal and additional axial force tothe wheel bearings.

In still another aspect of both the improved apparatus and powered axleassembly of the present invention, a support portion of the rotary unionassembly is provided over the axle spindle, enhancing the otherwiselimited space in drive axle designs between the end of the spindle andthe internal face of the axle plate, allowing for the inclusion ofbearings therebetween to reduce heat generated by contact between themoving and stationary parts and to cooperate with the annular sealingmember to reduce any adverse effects of offset wheel mountings on theseal(s) formed by the sealing member.

In another aspect of both the improved apparatus and powered axleassembly of the present invention, the adhesive and cohesive propertiesof lubricating oil are utilized in combination with the centrifugalforce generated by the rotating axle to draw oil provided about a lowerportion of the axle outwardly therefrom, past the sealing member in thecavity between the rotor and base, effecting lubrication of the sealingmember and dissipating heat generated by seal friction. The adhesiveproperty in the oil causes it to adhere to the component parts to effectlubrication while the cohesive property of the oil allows the oil to bedrawn by centrifugal force in a wick-like fashion to produce flow.

In still another aspect of the present invention, there is provided anapparatus for delivering air through a powered axle assembly, thepowered axle assembly including a drive axle which extends through anon-rotating structure and is powered for rotation with respect to thenon-rotating structure. The apparatus comprises a base, a locking ringfor attaching the base to a non-rotating structure and a rotor mountablefor rotation with the drive axle such that the rotor will rotate withrespect to the base and the locking ring and is configured so as todefine a radial projection extending between the base and locking ring.A pair of sealing members are disposed adjacent to and on opposed sidesof the radial projection on the rotor, one of the sealing rings beingcarried by said base and the other sealing ring being carried by thelocking ring. The base includes at least one air inlet configured fordelivering air into the radial extension in the rotor in a radialdirection and the rotor includes at least one air outlet for air flowoutwardly therefrom in an axial direction. The sealing rings form sealsbetween the rotating rotor and the stationary base and locking ring asthe rotor undergoes rotation with respect to the base and locking ring.

In another aspect of the present invention, there is provided animproved powered axle assembly including a drive axle which extendsthrough a non-rotating structure and is powered for rotation withrespect to the non-rotating structure. The improvement comprises a base,a locking ring for attaching the base to a non-rotating structure and arotor mountable for rotation with the drive axle such that the rotorwill rotate with respect to the base and the locking ring and isconfigured so as to define a radial projection extending between thebase and locking ring. A pair of sealing members are disposed adjacentto and on opposed sides of the radial projection on the rotor, one ofthe sealing rings being carried by said base and the other sealing ringbeing carried by the locking ring. The base includes at least one airinlet configured for delivering air into the radial extension in therotor in a radial direction and the rotor includes at least one airoutlet for air flow outwardly therefrom in an axial direction. Thesealing rings form seals between the rotating rotor and the stationarybase and locking ring as the rotor undergoes rotation with respect tothe base and locking ring.

Further aspects, features, and advantages of the present invention willbe apparent from the following detailed description taken in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cutaway elevational side view of a powered axle assemblyhaving an embodiment of the delivery apparatus of the present inventionincorporated therein.

FIG. 2 is another cutaway elevational side view of a powered axleassembly having the inventive air delivery apparatus of the presentinvention incorporated therein.

FIG. 3 is an exploded view of the inventive air delivery apparatus ofthe present invention.

FIG. 4 is an assembled cutaway elevational side view of the inventiveair delivery apparatus of the present invention taken about line 4 inFIG. 1 and illustrating the air flow therethrough.

FIG. 4A is an enlarged assembled cutaway elevational side view of aportion of the inventive air delivery apparatus of the present inventiontaken about line 4A in FIG. 4 and illustrating the air flowtherethrough.

FIG. 5 is an assembled cutaway elevational side view of the inventiveair delivery apparatus of the present invention taken about line 5 inFIG. 1 and illustrating the lubricating and cooling oil flowtherethrough.

FIG. 6 is an enlarged exploded cutaway elevational side view of aportion of the air delivery apparatus of the present invention separatedfrom the axle spindle and hub.

FIG. 7 is a perspective view of the rotor employed in the inventiveapparatus of the present invention.

FIG. 8 is a perspective view of the locking ring employed in theinventive apparatus of the present invention.

FIG. 9 is a perspective view of the stator employed in the inventiveapparatus of the present invention.

FIG. 10 is a perspective view of the annular double-lip seal employed inthe inventive apparatus of the present invention.

FIG. 10A is an enlarged partial perspective view of a portion of amulti-piece alternate embodiment of the annular double-lip sealillustrated in FIG. 10.

FIG. 11 is a cutaway elevational side view of a powered axle assemblyhaving an alternate embodiment of the inventive air delivery apparatusincorporated therein.

FIG. 12 is an exploded view of the alternate embodiment of the inventiveair delivery apparatus of the present invention illustrated in FIG. 2.

FIG. 13 is a sectional side view taken about the line 13 in FIG. 11.

FIG. 14 is a sectional side view taken about the line 14 in FIG. 11.

FIG. 15 is a perspective view of the rotor employed in the alternateembodiment of the present invention.

FIG. 16 is a perspective view of the stator and air inlet tube employedin the alternate embodiment of the present invention.

FIG. 17 is a perspective view of the locking ring employed in thealternate embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A preferred embodiment of the inventive apparatus 10 for delivering airthrough a powered axle assembly is illustrated in FIGS. 1-10. Theinventive apparatus 10, also referred to as a rotary union assembly, isshown in FIGS. 1 and 2 as installed in a typical powered tandem axleassembly 12 used on trucks and other vehicles. As will be understood bythose skilled in the art, the powered axle assembly 12 comprises: anon-rotating structure 14 (e.g. a spindle or other housing); a powereddrive axle 16 which extends through and rotates with respect to thenon-rotating structure 14; a drive axle hub 18, also known as the axleplate, which is provided on the outer end of and projects radiallyoutward from the drive axle 16; a wheel hub 20 which is secured to thedrive axle hub 18 for rotation with the powered drive axle 16; andtapered roller bearing(s) 22 which rotatably support the wheel hub 20 onthe axle spindle 14. The powered tandem axle assembly will also includea single or pair of wheels and tires 24 and 26 which will be mounted onthe wheel hub 20.

The rotary union assembly 10 is effective for allowing air from anonboard automatic tire inflation systems or another source automaticallyto flow through one or more air outlet tubes or other conduits 28 whichextend through the drive axle hub 18 to a leaking tire. Flexible hosesor other conduits 30 can be readily secured to the outer ends of the airoutlet tubes 28 for delivering air to the tires 24 and 26 of the poweredaxle assembly 12. As with the systems used heretofore for maintaininginflation in the tires of non-powered axle assemblies, check valves orother devices can be provided in the air lines 30 extending from the airoutlet tubes 28 in order to allow limited deflation but prevent completedeflation of the tires 24 and 26.

The embodiment of the rotary union assembly 10 illustrated in FIGS. 1-10comprises a rotor 32 (see FIG. 7) which is rotatably mounted proximatethe outer end of the axle spindle 14 about a stationary base 34 (seeFIG. 9) and is driven by the powered axle 16 such that the rotor 32rotates with respect to the base 34 and with respect to the axle spindle14. A locking ring 36 (see FIG. 8) is positioned about and threadablyengages an outer end portion 14′ of the spindle 14 and holds the rotor32 in place about the base 34 and secures the base to the spindle. Asillustrated in FIG. 4A, the inner downstream end of the locking ringdefines a radial end flange 35 that overlaps and mates with acorresponding flange 37 on the upstream end of the base. Thus, when thelocking ring 36 is threaded onto the end 14′ of the spindle, the base ispulled against the spindle and held in place by the locking ring. Inthis embodiment of the invention, the locking ring 36 is configured soas to also secure the rotor in place by cooperating with the rotor toreceive therebetween a roller bearing 38 in a press fitment within anopen annular area 39 between the locking ring and the upstream end ofthe rotor, as seen, for example, in FIG. 4.

The above described assembly defines an interior air chamber 42 betweenthe rotor 32 and base 34. An annular sealing member 44 (see FIG. 10) isprovided within the air chamber 42 for sealing the air chamber. An airpassageway 46 is machined or otherwise formed in the base 34 fordelivering air therethrough into the air chamber 42 in a radialdirection, as will be described.

In the embodiment of the present invention illustrated in FIGS. 1-10,the sealing member 44 preferably is of the double-lipped seal type andcan be formed of any suitable material for conforming to the walls ofthe air chamber 42 and providing a sealing interface between the base 34and the rotor 32 and, if utilized, with a pair of laterally disposedseal supporting rings 48′ and 48″ positioned adjacent to the opposedlateral sides of the sealing member 44. The material of which thesealing member 44 is formed will preferably have a low frictioncoefficient and high wear resistance. Examples of suitable materialsinclude, but are not limited to: polytetrafluoroethylene (PTFE);mixtures of PTFE, glass fiber, and molybdenum disulfide; mixtures ofPTFE and carbon; and rubber compounds such as VITON. The double-lippedseal 44 will most preferably be formed from PTFE impregnated withgraphite.

The seal supporting rings 48′ and 48″ may be utilized adjacent to thesealing member 44. These rings can be formed of a relatively rigidmaterial such as aluminum and are utilized to provide lateral supportfor the sealing member 44 and prevent axial distortion of the sealingmember 44 during use. Also, as shown in FIGS. 3, 4 and 5, an annularspacer 49 is secured to the rotor by tapered headed screws 51 and spansthe juncture between the rotor and the upstream seal supporting ring 48′so as to prevent the pressurized air in chamber 42 from distorting thesealing member 44 while providing a spacing 53 between the rotatingrotor 32, the sealing member 44 and upstream seal supporting ring 48′and the stationary locking ring 36 and roller bearing 38. As will belater described, spacing 53 forms a portion of the pathway for thelubricating oil for the rotary union assembly. In those applications,where there is inadequate room for the seal supporting rings or if forother reasons the supporting rings 48′ and 48″ are not utilized, thelateral side walls of the rotor 32, locking ring 36 and annular spacer49 can be configured so as to abut and cooperate with the opposing sidewalls of the sealing member 44 to provide the necessary lateral supportfor the sealing member.

The outer annular face 44′ of the sealing member 44 defines a centrallydisposed recessed annular outer air flow channel 45 therein and a pairof laterally spaced annular recesses 47 disposed on opposed sides ofchannel 45 in which a pair of o-ring seals 52 are retained. The opposedinner surface 44″ of the sealing member defines a pair of axially spacedand inwardly extending annular sealing lips 44 a and 44 b and an innerair flow channel 44 c therebetween. The o-rings 52 in the outer face ofthe sealing member bear against the annular interior surface 32′ of therotor in sealing engagement therewith while the extended sealing lips 44a and 44 b projecting from opposed sides of the inner face of thesealing member bear against and are in sealing engagement with the sidewalls of air chamber 42 or the seal supporting rings 48′ and 48″ (ifutilized) and with the outer surface 34′ of the base 34 on opposed sidesof the air outlet end 46′ of the air passageway 46 therein as is alsobest seen in FIGS. 4 and 4A. As illustrated therein, the sealing lips 42a and 44 b preferably comprise radial portions 44 a′ and 44 b′projecting inwardly from opposed sides of the sealing member that mergeinto inwardly inclined portions 44 a″ and 44 b″ that terminate ininwardly facing opposed distal end portions 44 a′″ and 44 b′″. Uponpressurized airflow being directed into air chamber 42 through air flowchannel 44 c and causing a pressure buildup within air chamber 42, sucha double lip seal configuration provides significantly enhanced sealingengagement between the stationary and rotary structures of the driveaxle assembly. A plurality of equidistantly spaced air passageways 50(four being shown) extend radially through the sealing member 44,communicating the inner air flow channel 44 c with the outer channel 45.

While the sealing member 44 is generally illustrated as being ofsingle-piece construction, to facilitate the formation of the sealingmember, it may be desirable to form the sealing member multiple sectionswhich could be held together by mechanical or chemical means. Oneexample of such a configuration is illustrated in FIG. 10A wherein thesealing member 244 is comprised of three sections 244 a, 244 b and 244c. The two outer sections 244 a and 244 c can be of a configurationsubstantially identical to the lateral portions of the single-piecesealing member 44 and can be formed of the same material as sealingmember 44. For cost savings, the center section 244 b preferably can beformed of a rigid metal or plastic material, such as aluminum orDelrin®, as center section 244 b is not in contact with any stationaryelements. Seal section 244 b defines a recessed annular air channel 245extending about the perimeter thereof and a plurality of equidistantlyspaced air passageways 250 extending radially therethrough andcommunicating with annular channel 245, similar to the annular channel45 and passageways 50 in the single-piece embodiment of sealing member44. The two outer sections 244 a and 244 c each define an annular recess247 extending about the perimeter thereof for retaining an o-ring (notshown) therein in the same manner as the single-piece sealing memberdefines annular recesses 47 for retaining o-rings 52. The opposed innersurfaces of lateral sealing sections 244 a and 244 c would define thetwo lip seals 244 a′ and 244 b′ for the multiple piece sealing member244. Upon the three sections 244 a-c being held in adjacent axialalignment, the resultant sealing member 244 can form the identicalconfiguration as sealing member 44 and functions in the same manner.

In use, the sections of sealing member 244 are positioned within airchamber 42 and can be held together in axial alignment by means of aplurality of equidistantly spaced threaded fastening members (not shown)extending through an annular spacer (not shown) like spacer 49 andengage an adjacent seal support ring (not shown) like ring 48′, suchthat upon tightening the fastening members, the extended ends thereofwill abut and urge the adjacent seal support ring, the sealing membersections 244 a-c and a second seal support ring like ring 48″ against adownstream portion of the rotor and thereby hold each of the componentsof the sealing member together and in place. By utilizing such amulti-piece configuration for the sealing member, the lateral portions244 a and 244 c thereof can be economically formed by injection moldingand readily secured in place, as described, whereas the process forforming the double-lip seal sealing member 44 of a single-piececonstruction may be more time consuming and costly. It is to beunderstood that the term sealing member is used herein to describe aseal that can be of single-piece construction or that can comprise twoor more components held together in an adjacent disposition.

The seal supporting rings 48′ and 48″ that can be employed adjacent tothe sealing member 44 also preferably define inwardly tapered annularfoot portions 48 a extending about the interior perimeters of the sealsupporting rings for directing the individual lip seals 44 a and 44 binwardly along and against the base 34 to increase the area of contacttherewith and provide a natural, outward flex in the sealing lipsthereby enhancing the sealing engagement of the sealing member 44 withthe base. Rotor 32 is preferably provided with a pair of air outletopenings 60 in the annular downstream end face 32′ thereof and with aplurality of equidistantly spaced air flow apertures 54 in the innerannular surface 32″ thereof (two such apertures being shown) forcommunicating the air passageway 46 through base 34 with the air outlettubes 28 via the air chamber 42 between the base and rotor, the radialpassageways 50 and the recessed channel 45 in the sealing member 44 andapertures 54, an annular air cavity 56 and air outlet openings 60 in therotor 32 (see air flow arrows in FIGS. 4 and 4A).

The threaded attachment of the above described assembly onto the spindleis made difficult by the rotatable mounting of the rotor 32 with respectto the locking ring 36 and the base 34. The resulting assembly isdifficult to grasp and rotate into threaded engagement with the spindle.To assist the installer, Applicant has provided a plurality of installpin holes 73 extending axially through a perimeter portion of the rotor32 (four being shown) and a corresponding plurality of install pin holes75 in an outer portion of the locking ring 36 such that upon rotatingthe rotor with respect to the locking ring, the install pin holes 73 inthe rotor can be brought into axle alignment with the install pin holes75 in the locking ring (see FIGS. 3, 7 and 8). By extending a suitabletool 77, such as a Phillips screwdriver, through one of the install pinholes 73 in the rotor, rotating the rotor until the screwdriver isaxially aligned with one of the pin holes 75 in the locking ring andthen inserting the screwdriver into the aligned pin install hole 75,further relative rotation between the rotor and the locking ring as wellas the other components of assembly is prevented. By then inserting asecond such tool 77 through a second pair of aligned pin install holes73 and 75 in the rotor and the locking ring, the rotary union assemblycan be threadably engaged with and tightened about the spindle using thetwo tools, whereupon the tools can be withdrawn. Such an assemblyprocess is schematically illustrated in FIG. 6. If desired, an assemblytool (not shown) could be fabricated to effect such mounting. Such atool, for example, could comprise a planar ring and two or moreperpendicularly mounted install pins secured to and projectingperpendicularly from the ring for insertion into aligned pairs of thepin installment holes in the rotor and locking ring. An annular or othersuitable gripping surface for rotating the tool to effect installationalso could be provided. To prevent the rotary union assembly frombacking off its threaded engagement with the axle spindle during use, aplurality of jam screws 40 preferably can be extended through acorresponding plurality of holes 38 a formed in the base 34 (see FIGS. 6and 9) so as to threadably engage the axle spindle 14.

In a modification (not shown) of the present invention, the orientationof the sealing member 44 within air chamber 42 could be reversed suchthat the previously described outer face 44′ of the sealing memberdefining the recessed channel 45 and carrying o-rings 50 could bedisposed against the outer surface of the base 34, preferably within arecessed area formed on the outer surface 34′ of the base 34 to inhibitlateral movement of the sealing member, such that the o-ring seals 52then would bear against the base on opposed sides of the air outlet end46′ of the air passageway 46 in sealing engagement with the base. Theextended sealing lips 44 a and 44 b on sealing member 44 would bearagainst the interior surface 32′ of the rotor in sealing engagementtherewith on opposed sides of the air flow apertures 54 disposedtherein.

The air outlet tubes 28 of the inventive apparatus extend through axialbores 58 formed through the drive axle hub 18. The inlet ends 28′ of thetubes extend into corresponding air outlet passageways or openings 60provided in the rotor so as to communicate the inlet ends of the tubes28 with air cavity 56 and apertures 54 within the rotor 32. Thus, in thepresent embodiment, radial passageways 50, the recessed channel 45′ inthe sealing member 44, apertures 54, air cavity 56 and openings 60collectively define air outlets for rotor 32.

Preferably, the air outlet tubes are mounted in a manner so as to permitthe tubes to pivot slightly to some degree with respect to the driveaxle hub or plate. To provide such movement, the upstream ends of thetubes can threadably engage the rotor about openings 60 and the axle hubcan be provided with axle inserts 62 that are held in bores 58 bybrazing, a press fitment or an adhesive such as a liquid solderadhesive. The axle inserts 62 threadably engage an axle plug 64 andcarry a pair of o-ring seals 66 in a parallel disposition (see FIG. 4).A slight clearance 57 preferably is provided between the outer surfaceof the outlet tubes and their respective axle plugs whereby the o-ringscan allow for the slight flexing of the outlet tubes while maintainingoil-tight seals about the tubes.

In addition to permitting air flow to the exterior of the powered axleassembly, the positioning of the outlet air tubes 28 through the driveaxle hub 18 also links the rotor 32 with the powered drive axle 16 tothus cause the rotor to rotate with the drive axle and to align therotor relative to the axis of rotation of the drive axle. Because of theradial entry of air into the air chamber 42 through the sealing member44 and into the air cavity 56, there is minimal outward axial thrustcreated by the pressurized air flow on the air tubes, simplifying themounting of the air outlet tubes to the rotor.

Air from an onboard automatic tire inflation system or other source issupplied to the rotary union assembly 10 by air inlet tube 72 which canbe attached to the base 34 by means of an air inlet tube fitting 74 orbrazed joint that can threadably engage the air inlet end 46″ of airpassageway 46 within the base. An o-ring seal 76 can be disposed betweenthe downstream end of the air inlet 74 and the surrounding base 34 as isalso shown in FIGS. 4 and 4A.

Thus, in the event that a tire leak or puncture occurs or a tirepressure adjustment is needed, make-up air from the onboard automatictire inflation system will flow sequentially through the air inlet tube72, the air passageway 46 in the base 34 which directs the pressurizedair into air chamber 42 in a radial direction, urging the sealing member44 outwardly against the interior annular surface 32′ of the rotor 32,against the sealing supporting rings 48′ and 48″ (if utilized) andspacer 49 and the extended sealing lips 44 a and 44 b outwardly andinwardly against the seal supporting rings 48′ and 48″ (again, ifutilized) and base 34. The forces acting on the sealing member 44 arebalanced and well contained by the structures surrounding the sealingmember. Air flow proceeds from chamber 42 radially through thepassageways 50 in the sealing member into and about the annular recessedchannel 45 in the annular outer face 44′ of the sealing member andthrough the openings 54 in the rotor as the rotor and sealing memberrotate together with respect to the base and locking ring. The airpassing from channel 45 outwardly through the air openings 54 in therotor enters the air cavity 56 in the rotor and exits the air outlettubes 28 via openings 60 in the rotor to the air lines 30 and tire(s) 24and/or 26.

Also, as seen in FIG. 4, an opening 68 can be provided in the outersurface of the rotor 32 in axial alignment with one of the air flowapertures 54 in the rotor 32 to facilitate the drilling of the flowapertures 54. Opening 68, is covered by a plug 70 after assembly toprevent air leakage therethrough. Plug 70 is preferably secured bythreaded engagement with the rotor about opening 68. Also, rather thanusing an air inlet tube 72, an inlet air passageway for delivering airto the rotary union assembly 10 could alternatively be drilled or boredaxially through the non-rotating axle spindle 14 itself.

In order to lubricate and cool the rotor 32, sealing member 44 andassociated components, the present invention utilizes the rotating axlewhile taking advantage of the adhesive and cohesive properties of theoil to lubricate and cool these components. The lower portion of thespindle in which the axle rotates, is partially filled with lubricatingoil. As the axle rotates within the spindle, the axle acts as an oilslinger, throwing the oil about the spindle. The distribution of the oilabout the rotary union assembly for lubrication and cooling isillustrated in FIG. 5 and the particular oil flow holes provided in thecomponents of the rotary union are illustrated in FIGS. 7-10. As seentherein, a plurality of radially oriented oil flow holes 80 (four beingshown) are provided in the outer annular surface of the rotor 32. Acorresponding plurality of axially oriented oil flow holes 76 areprovided in the locking ring 36 (see FIGS. 3 and 8) and a largerplurality of radially oriented oil flow holes 78 are provided in theannular surface of the base 34 (see FIGS. 3 and 9). As a result, the oilthrown by the rotating axle passes through and about the base and therotor and about the sealing member and roller bearing 38 as illustratedby the arrows in FIG. 5, effecting a lubricating and cooling of therotating and adjacent components. Thus, the adhesive property in thelubricating oil causes the oil to adhere to the various components toeffect the lubrication and cooling thereof while the cohesive propertyof the oil allows the oil to be drawn by the centrifugal force generatedby the axle in a wick-like fashion through and about the components asabove described and illustrated in FIG. 5.

An alternate embodiment of the inventive apparatus is illustrated inFIGS. 11-17. As seen therein, the modified rotary union assembly 100primarily differs from the assembly 10 of the prior embodiment in theconfiguration and sealing engagements of the respective sealing members.Unlike sealing member 44 which rotates with the rotor 32 and effects arotating seal with a stationary base, the sealing member in thisalternate embodiment is comprised of a pair of stationary annularsealing members 144 a and 144 b in the form of rings or discs,preferably rectangular in cross-section, that effect sealing engagementswith the rotating rotor 132.

The annular sealing members 144 a and 144 b can be formed of the samematerial as seal 44 with sealing member 144 a being carried by thelocking ring 136 and sealing member 144 b being carried by the base 134.(See, e.g., FIG. 13.) Each of the two sealing members can be held in apress fitment within correspondingly configured areas within the lockingring and base such that the opposed inner surfaces of the two sealingmembers bear against opposed side walls of a radial projection 132 aextending inwardly about the annular interior surface 132′ of the rotor132 as seen, in FIGS. 13 and 14. A pair of opposed radially aligned airflow passageways 150 preferably extend through the rotor 132 and radialprojection 132 a, communicating an air passageway 146 in the base 134with the air outlet tubes 28 via cavity 156 and openings 160 in therotor 132 for providing pressurized air flow to the air lines and tiresas previously described in discussing the prior embodiment of FIGS.1-10.

To maintain the rotary seals effected by sealing members 144 a and 144 bwith the opposed side walls of the radial projection 132 a on rotor 132,a plurality of threaded fastening members 141 (one being shown in FIG.14) can threadably engage and extend inwardly through the base 134 andinto locking ring 136 so as to prevent axial separation between the baseand locking ring which would otherwise cause the seals to fail. Toprevent the rotary union assembly 100 from backing off its threadedengagement with the axle spindle during use, a plurality of jam screws(not shown) can be extended through a corresponding plurality of holes(also not shown) formed in either the base 134 or the locking ring 136so as to threadably engage the axle spindle 14 and prevent relativerotation therebetween. A similar securement of the base 34 to thelocking ring 36 was discussed earlier therein with respect to rotaryunion assembly 10. Also, a plurality of install pin holes (not shown),can extend axially through a perimeter portion of the rotor 132 and thelocking ring 136 to accommodate a suitable tool for holding the rotor,base and locking ring in a fixed relative disposition to assist theinstaller in effecting the threaded engagement of the rotary unionassembly 100 onto the spindle 14 in the same manner as described earlierherein in connection with the threaded attachment of the rotary unionassembly 10. The remaining features of rotary union assembly 100 andsurrounding environment are substantially the same as in assembly 10 andin such instances, the same reference numerals used in FIGS. 1-10 aregenerally carried over into FIGS. 11-17. Rotary union assembly 100, likeassembly 10, also includes lubrication passageways which are illustratedby the oil flow arrows in FIG. 14 and again utilizes the previouslydiscussed oil slinger effect provided by the rotating axle to lubricateand cool adjacent rotating and stationary components.

The use of the two annular sealing members 144 a and 114 b in sealingengagement with the opposed side walls of a radial projection 132 aextending about the rotor 132 through which the pressurized air isradially directed into the interior of the rotary union assembly 100provides even greater protection against possible air leakage in theevent of run off resulting from off center wheel mountings.

Although the present invention has been described by way of exemplaryembodiments, it should be understood that many changes and substitutionsmay be made by those skilled in the art without departing from thespirit and the scope of the present invention, which is defined by theappended claims.

What is claimed is:
 1. In a powered axle assembly including a drive axlewhich extends longitudinally through a non-rotating structure and ispowered for rotation within said non-rotating structure, a drive axlehub provided at an axial outer end of said drive axle which rotates withsaid drive axle and is positioned outside of an outer end of saidnon-rotating structure, a wheel hub secured to said drive axle hub andextending axially rearward, and at least one bearing which supports saidwheel hub on an exterior of said non-rotating structure for rotation ofsaid wheel hub around said exterior of said non-rotating structure, theimprovement comprising: a base operatively connected to saidnon-rotating structure and having said drive axle extendingtherethrough, said base being positioned within an interior of saidwheel hub; a rotor having said drive axle extending therethrough andmounted within said interior of said wheel hub for rotation with saiddrive axle hub such that said rotor will rotate with respect to saidbase, said rotor being configured so as to form an air cavity therein,said air cavity encircling said drive axle and being located within saidinterior of said wheel hub; said base including at least one airpassageway extending therethrough for delivering air to said air cavityin a radial direction relative to the drive axle; said rotor includingat least one air outlet for air flow out of said air cavity and definingan annular projection extending radially from and about said rotor andat least one air passageway extending radially through said projectionand communicating said at least one air passageway in said base withsaid air cavity and with said at least one air outlet; a locking ringoperatively securing said base to said non-rotating structure and saidrotor proximate said base; a first annular sealing member carried bysaid base; a second annular sealing member carried by said locking ring;and wherein said first and second sealing members abut and form sealingengagements with opposed sides of said annular projection on said rotoras said rotor rotates with respect to said base and said sealingmembers.
 2. The powered axle assembly of claim 1 wherein said at leastone passageway extending through said base defines an upstream axialportion for receiving air from a pressurized source and a downstreamradial portion for directing air from said axial portion radially intosaid air cavity through said at least one air passageway in said radialprojection.
 3. The powered axle assembly of claim 1 wherein theimprovement further comprises a bearing disposed in a press fitmentbetween portions of said locking ring and said rotor so as to urge saidportions of said locking ring and rotor in opposed radial directionsthereby effecting the operative securement of said rotor proximate saidbase while allowing rotation of said rotor with respect to said base. 4.The powered axle assembly of claim 1 wherein said locking ringthreadably engages a portion of the non-rotating structure and includinga plurality of fastening members securing said locking ring to said basewhereby axial separation of said locking ring and said base is preventedand the sealing engagement of said sealing ring with said radialprojection on said rotor is maintained.
 5. The powered axle assembly ofclaim 1 wherein at least a portion of the interior of the non-rotatingstructure contains sufficient lubricating oil such that rotation of theaxle through the oil slings droplets of oil outwardly therefrom andincluding a plurality of oil passageways communicating with the interiorof said non-rotating structure and extending about and between saidrotor, said first and second sealing members, said base, and saidlocking ring, said oil passageways receiving and directing the dropletsthroughout said oil passageways thereby lubricating said rotor and saidsealing member for rotational movement with respect to said base andsaid locking ring and dissipating heat generated by such rotation. 6.The powered axle assembly of claim 5 wherein the improvement furthercomprises a bearing disposed in a press fitment between portions of saidlocking ring and said rotor so as to urge said portions of said lockingring and rotor in opposed radial directions thereby effecting theoperative securement of said rotor proximate said base while allowingrotation of said rotor with respect to said base.
 7. In a powered axleassembly including a drive axle which extends longitudinally through anon-rotating structure and is powered for rotation within saidnon-rotating structure, a drive axle hub provided at an axial outer endof said drive axle which rotates with said drive axle and is positionedoutside of an outer end of said non-rotating structure, a wheel hubsecured to said drive axle hub and extending axially rearward, and atleast one bearing which supports said wheel hub on an exterior of saidnon-rotating structure for rotation of said wheel hub around saidexterior of said non-rotating structure, the improvement comprising: abase operatively connected to said non-rotating structure and havingsaid drive axle extending therethrough, said base being positionedwithin an interior of said wheel hub and defining at least onepassageway extending therethrough for communication with a pressurizedair source; a rotor having said drive axle extending therethrough andmounted within said interior of said wheel hub for rotation with saiddrive axle hub such that said rotor will rotate with respect to saidbase, said rotor defining at least one air outlet therein and an annularprojection extending radially from and about said rotor and at least oneair passageway extending radially through said projection andcommunicating said at least one air passageway in said base with said atleast one air outlet; and a pair of annular sealing members fixed in anaxially aligned disposition, said sealing members abutting and formingsealing engagements with opposed sides of said annular projection onsaid rotor as said rotor rotates with respect to said base and saidsealing members.
 8. The powered axle assembly of claim 7 including alocking ring operatively securing said base to said non-rotatingstructure and said rotor proximate said base and a bearing disposed in apress fitment between portions of said locking ring and said rotor so asto urge said portions of said locking ring and rotor in opposed radialdirections thereby affecting the operative securement of said rotorproximate said base while allowing rotation of said rotor with respectto said base.
 9. The powered axle assembly of claim 8 wherein one saidsealing members is carried by said base and the other of said sealingmembers is carried by said locking ring.